EP1561011B1 - Pivoting actuator system for controlling the stroke of a gas exchange valve in the cylinder head of an internal combustion engine - Google Patents

Abstract

The invention relates to a pivoting actuator system (1) for controlling the stroke of a gas exchange valve (2) in the cylinder head (3) of an internal combustion engine. Said system consists of a pivoting motor (4), equipped with a shaft (5), on which an actuating element (6) with a control trajectory (7) for opening the gas exchange valve (2) is located. The invention is characterised in that a second actuating element (8) with a second control trajectory (9) is provided on the first actuating element (6). The inventive configuration of the pivoting actuator system permits the amount of current required at low speeds to be reduced and the preparation of the mixture to be improved.

Description

The invention relates to a Schwenkaktor device for stroke control of a gas exchange valve in a cylinder head of an internal combustion engine according to the features in the preamble of claim 1.

It starts from the US 5,873,335. In this is a Schwenkaktor device for stroke control of a gas exchange valve in a cylinder head of an internal combustion engine, comprising a pivot motor with a shaft to which an actuator is arranged with a control track is described. The actuating element is used to open a gas exchange valve, wherein a second actuating element with a second control path is arranged on the first actuating element.

A disadvantage of the described Schwenkaktor device is that the gas exchange valve despite the o. G. Design, only with a Ventilhubverlauf is actuated.

Object of the present invention is to further develop a generic Schwenkaktor device to the effect that for the gas exchange valve different Ventilhubverläufe are possible.

This object is solved by the features in the characterizing part of patent claim 1.

The invention extends the existing Schwenkaktor device by a second actuator in the opposite direction of rotation with a smaller stroke relative to the main cam. This second actuator does not fully open the valve and is used only for small strokes in the range of low engine speeds. At low speeds of the internal combustion engine, the Schwenkaktor device is energized so that the shaft pivots only in the direction of the second actuating element, while at high speeds is pivoted exclusively in the direction of the first actuating element. Due to the low stroke, the Schwenkaktor device consumes less power at low speeds advantageously.

Due to the embodiment according to claim 2, the two actuators form a double cam, which is bumpless actuated in two directions. In addition, the production of such a designed double control track whose Nullhubbereiche are adjacent, simple and inexpensive.

With an embodiment according to the claims 3 to 6, the current consumption at low speeds is low. Furthermore, valve noise generated by opening the gas exchange valve on the valve seat is reduced by the design according to the invention. The second actuator balances the moments of the spring element, an actuator spring, against the moments of the valve spring. Thus, the resulting torque on the camshaft is nearly zero, depending on tolerances, and thus the camshaft can be kept almost de-energized in any angular position of the second actuator. Such a system has a low dynamics, since this is built up solely by the moment structure of the swing motor (by energization). Another advantage is the improvement in the gas dynamics when changing the charge to name, as due to the small valve lift supersonic speeds in the valve gap can be generated, which contribute significantly to a good mixture preparation positive. In particular, in an embodiment according to claim 5 system overshoots do not affect, since the valve is not changed in these areas.

In order to improve the low dynamics of the second actuating element, the second control track according to the claims 7 to 9 is configured. For this is the Tax track divided into two areas. In the first stroke range, from zero lift or a defined value (eg from 0.6 mm to 1.5 mm lift height), the kinematics torque of the spring element is compensated only to a small extent so that a spring-induced acceleration is impressed on the swivel actuator device , In the second stroke range (eg from 1.5 mm to approx. 3.5 mm), the kinematics moment of the spring element is overcompensated, so that a spring-related deceleration is impressed on the pivoting actuator device over this stroke range. With this configuration, it is possible in a simple manner to positively influence the dynamics of the Schwenkaktor device, especially for small valve strokes.

According to claim 10, it is possible to arrange the two actuating elements either radially on the outer circumference of the shaft, whereby a plurality of gas exchange valves can be operated by a Schwenkaktor device or attach to the frontal surface of the shaft a slide track with which a single gas exchange valve is controlled.

In the arrangement of a force transmission element between the actuating element and gas exchange valve according to claim 11 and 12, the internal friction of the system is reduced.

Advantageously, the Schwenkaktor device according to the invention can be arranged according to claim 13, both the inlet side and the exhaust side in the cylinder head of the internal combustion engine. This common part principle allows cost-effective production.

In the following, a preferred embodiment is explained in more detail with reference to a single figure.

Fig. 1 shows a schematic representation of a Schwenkaktor device 1 according to the invention in the installed position in a cylinder head 3. The Schwenkaktor device 1 consists essentially of a pivot motor 4 with a stator, not shown, and a rotor, not shown. The rotor is fixedly connected to a shaft 5 with a common axis of rotation 5a. The shaft 5 has radially at its periphery an actuating element 6 with a first control track 7, a half cam on. The first control path 7 is divided into three individual regions, a first zero-stroke region 7a, a first stroke region 7b and a full-stroke region 7c. A second actuating element 8 with a second control path 9 adjoins the first zero-stroke region 7a in the opposite direction of rotation. The second control track 9 is likewise subdivided into three areas, a second zero stroke area 9a, a second stroke area 9b and a partial lift area 9c. The second stroke region 9b is in turn divided into an acceleration stroke region 9b ', which adjoins the second zero stroke region 9a, followed by a delay stroke region 9b "The first zero stroke region 7a and the second zero stroke region 9a adjacent thereto have the same constant radius" R1 ". The distance between the first control track 7 in the first stroke region 7b increases in accordance with a cam contour via a rotation angle in the direction of the full stroke region 7c The full stroke region 7c following the first stroke region 7b in turn has a constant radius "R2" Radius difference between R2 and R1 corresponds to a height "h ₁ ", corresponding to a maximum gas exchange valve lift The second stroke region 9b adjoining the second zero stroke region 9a also has a cam contour, that is, the distance of the control path 9 from the rotation axis 5a increases in the lifting area 9b via a twist angle in the direction Teilhu b range 9c. The acceleration stroke region 9b 'has a degressive, the delay stroke region 9b "a progressive radius increase. Of the Verzögerungshubbereich 9b "subsequent partial stroke 9c has a constant radius" R3 "in respect to the rotation axis 5a. The radius difference between R3 and R1 corresponds to a height" h ₂ ", a middle gas-exchange valve. The Beschleunigungshubbereich 9b 'begins in This example starts from a stroke of 0.6 mm and extends up to a lifting height of 1.5 mm The delay stroke range 9b "starts from a lifting height of 1.5 mm and extends up to a lifting height of 3.5 mm. While the acceleration stroke range 9b 'compensates for the kinematics torque of the spring element only to a small extent and thus imposes spring-induced acceleration on the system, the kinematic moment of the spring element 12 is overcompensated in the deceleration stroke range 9b "and thus the system is impressed with spring-induced deceleration over this stroke range 9b 'and the delay stroke 9b "can occupy different angular sections of the control track 9 depending on the internal combustion engine or omitted entirely in favor of a normal cam contour.

In the illustration, the second Nullhubbereich 9a with a roller element 10a of a power transmission element 10, a roller cam follower in operative connection. The power transmission element 10 is based, on the one hand, on a clearance compensation element 14, a hydraulic valve clearance compensation element, which is arranged stationarily in the cylinder head 3 and, on the other hand, on a valve stem end of a gas exchange valve 2 which is held in the closed position by a valve spring 11. Further, on the shaft 5, a stationary support member 13 on which a spring element 12, a leg spring, on the one hand is supported, while on the other hand it is fixed in position on the cylinder head 3.

During operation of the internal combustion engine, the swivel motor 4 pivots at high requested load or speed in the direction of the full-stroke range 7c and at a lower requested load or speed in the direction of the partial lift ranges 9c. In the periodic pivoting movement in one direction or the other, the gas exchange valve 2 is opened in accordance with the control tracks 7 and 9, respectively. The pivoting movement of the swivel motor 4 is assisted during opening by the spring element 12 and the energy stored in the spring element 12 is delivered to the valve spring 11 during the opening process. When closing, while pivoting in the direction First and second Nullhubbereich 7a, 9a, the valve spring 11 is the stored energy in her largely to the spring element 12 from. By this spring-mass-spring-oscillation system, the energy requirement of the swing motor 4, especially at low valve lift, very low.

Subsequent partial lifting area 9c is a torque-neutral cam area in which electroless holding of gas exchange valve 2 in the open position, at maximum partial lift, especially at low engine speeds and high loads, is made possible. The height h _{2 of} the Teilhubbereiches 9c is designed according to internal combustion engine-dependent parameters. For the intake side of an internal combustion engine, the acceleration stroke region 9b 'of the second actuating element 8 can be made smaller in magnitude than the region of the deceleration stroke region 9b. "In this way, a variability of the second control path 9 and thus a better mixture control of the internal combustion engine can be achieved the exhaust side of an internal combustion engine, the Beschleunigungshubbereich 9b 'and the Verzögerungshubbereich 9b "have the same amount of work to achieve the highest possible dynamics of Teilhubbewegung, and thus expand the operating range of Teilhubbetriebes from idle to the highest possible speeds.

Due to the small, variable strokes, the load control of the internal combustion engine is simpler and allows more fuel-efficient operating points in the lower load range. Another advantage of the Schwenkaktor device 1 according to the invention is the lower power consumption at low speeds at small valve strokes against full valve lifts to mention. Due to the small air gap with a small valve lift of the inlet valve, it is possible to achieve supersonic inlet flow rates which improve the mixture preparation and thus reduce the emissions of the internal combustion engine. A further improvement results from opening the intake valve twice, a first time to draw in the combustion air and a second time to swirl the combustion air with fuel. This leads to a significantly improved mixing of air and fuel and thus to a more uniform combustion. On the exhaust side of the internal combustion engine, the opening speed of the valve movement can be reduced if desired, and thus reduces the Vorlassausstoß in the exhaust system become. Thus, the acoustic excitation of the exhaust system can be reduced and the overall noise level of the internal combustion engine can also be reduced.

LIST OF REFERENCE NUMBERS

1

Swivel actuator device

2

Gas exchange valve

3

cylinder head

4

swing motor

5

wave

5a

axis of rotation

6

actuator

7

first control track

7a

first zero stroke range

7b

first stroke range

7c

full lift

8th

Second actuator

9a

Second zero stroke range

9b

Second stroke range

9b '

Beschleunigungshubbereich

9b "

Verzögerungshubbereich

9c

partial stroke

10

Power transmission element

10a

roller element

11

valve spring

12

spring element

13

supporting

14

Lash adjuster

Claims (13)

1. A swivel actuator device (1) for controlling the stroke of a gas change valve (2) in a cylinder head (3) of an internal combustion engine, the device comprising a swivel motor (4) with a shaft (5) bearing an actuating element (6) with a first cam track (7) for opening the gas change valve (2), wherein the first cam track (7) is divided into a first zero stroke region (7a) and a first stroke region (7b),
   characterised in that a second actuating element (8) disposed on the first actuating element (6) has a second cam track (9) for opening the gas change valve (2), and the second cam track (9) is divided into at least one second zero stroke region (9a) and a second stroke region (9b).
2. A device according to claim 1,
   characterised in that the second zero stroke region (9a) is disposed on the first zero stroke region (7a) of the first cam track (7).
3. A device according to claim 1 or claim 2,
   characterised in that the first cam track (7) has a full stroke region (7c) and/or the second cam track (9) has a part stroke region (9c).
4. A device according to claim 3,
   characterised in that the full stroke region (7c) is disposed on the first stroke region (7b) and the part stroke region (9c) is disposed on the second stroke region (9b).
5. A device according to any of the preceding claims,
   haracterised in that the height (h₂) of the part stroke region (9c) is less than the height (h₁) of the full stroke region (7c).
6. A device according to any of the preceding claims,
   characterised in that the height (h₁) of the full stroke region (7c) is the maximum stroke height of the gas change valve (2).
7. A device according to any of the preceding claims,
   characterised in that the second stroke region (9b), starting from the second zero stroke region (9a), is divided into an acceleration stroke region (9b') and an adjoining deceleration stroke region (9b").
8. A device according to claim 7, wherein the shaft (5) is rotatable around an axis (5a),
   characterised in that in the acceleration stroke region (9b') the distance of the cam track (9) from the axis (5a) increases degressively over a torsion angle in the direction towards the part stroke region (9c).
9. A device according to claim 7,
   characterised in that in the deceleration stroke region (9b") the distance of the cam track (9) from the axis (5a) increases progressively over a torsion angle in the direction towards the part stroke region (9c).
10. A device according to claim 5,
    characterised in that the actuating element (6) and the second actuating element (8) are disposed radially or axially on the shaft (5).
11. A device according to any of the preceding claims, characterised in that a force transmitting element (10) is disposed between the actuating element (6, 8) and the gas change valve (2).
12. A device according to claim 11,
    characterised in that the force transmitting element (10) is a drag lever or a roller drag lever or a rocker arm.
13. A device according to any of the preceding claims, wherein the internal combustion engine has inlet gas change valves and outlet gas change valves,
    characterised in that the swivel actuator device (1) is mountable on inlet gas change valves and/or outlet gas change valves.

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